Interactions among smoke,radiation,and meteorology in the Canadian wildfires

Abstract

The record-breaking 2023 Canadian wildfires attracted considerable attention; however, the bidirectional feedbacks between wildfires and meteorology remain unclear. Here, we use the fully coupled Weather Research and Forecasting model with Chemistry (WRF-Chem) to investigate the dynamic interactions among wildfire emissions, aerosol–radiation interactions (ARI), and meteorological responses during this extreme event. The model reasonably reproduced the key spatial and temporal characteristics of wildfire smoke aerosols. Results show that wildfire aerosols caused substantial shortwave radiative perturbations, characterized by strong surface and top-of-atmosphere cooling, with a domain-averaged 8-day mean shortwave radiative perturbation reaching −165 W m⁻², and pronounced atmospheric heating of up to +140 W m⁻². These effects spatially aligned with regions of elevated optical depth (AOD). The atmospheric heating, primarily driven by light-absorbing carbonaceous aerosols (CAs), enhanced atmospheric stability and suppressed turbulent mixing, while also leading to reduced cloud formation and drying of the upper troposphere. As a result of the enhanced stability, the planetary boundary layer height (PBLH) decreased locally by up to ∼500 m, accompanied by reduced near-surface wind speeds. Importantly, increased humidity and weakened winds suppressed fire potential, suggesting that dense smoke plumes modified local meteorology in ways that inhibited further wildfire spread. These findings highlight the critical role of fully coupled models in capturing the complex wildfire–aerosol–radiation–meteorology feedback loop and emphasize the importance of representing two-way fire–weather interactions in future wildfire prediction and mitigation efforts.